Last month we tore down the rear suspension on “Scarlett,” our ’72 coupe project car, so we could install a Van Steel coilover conversion. At last count, we were six hours of labor into the project, having removed everything down to the trailing arms and then shipped those out to Van Steel to get the bearings rebuilt.
For some reason, I was under the impression this was the hard part. But while the teardown procedure was no doubt challenging, getting the new rear components in, bleeding the brakes, and then swapping out the front coil springs for lower-rate units tacked on 26 additional hours of labor, for a total of 32 since starting on the rear—not counting trips to the machine shop, parts store, and alignment rack.
The Van Steel trailing arms, which are built of heavy-duty ¼-inch steel, came with Bendix factory-style brake rotors installed, and the runout already checked. Since we’re running a Wilwood setup, we needed to swap out the rotors, which means checking the runout again to make sure they’re running true.
To do that, slip the rotor over the lugs and bolt it in place. Mount a dial indicator on the hub or trailing arm, then bring the indicator in contact with the rotor, set at zero, and rotate the rotor to make sure there’s no more than 0.005-inch difference in the reading. If there is, remove the rotor, realign it a couple of lugs over, and reinstall it. Tighten the lug nuts back down, and try again: If that doesn’t work, you’ll have to remove material from the rear of the rotor where it seats on the hub. (Since I didn’t have a dial indicator, I took the assemblies to North Georgia Machine, where a quick check showed the runout was well within spec.)
Once that’s done, mark the hub and rotor so you know how to index the latter for reassembly. You’ll want to remove it before installing the trailing arm to reduce the amount of weight you’re wrestling with.
Before installing the trailing arm, it’s a good idea to clean out the frame pocket and inspect the mounting and cotter-pin holes to make sure everything will go into place. On Scarlett, the inboard cotter-pin hole on the passenger side was only half there, and had to be drilled out. Now is also a good time to drill out the factory upper shock mount to 0.5-inch. Just make sure you don’t punch through into the fiberglass on the inboard side of the mount.
Next, slip the front of the trailing arm into the frame pocket and slide the cross bolt in to hold it in place. This is going to take a little jockeying around, so find a good way to support the weight, and get comfortable. Once the bolt slips into place, get the nut started and slide in the alignment shims. While you may be able to reuse the original bolts and shims, I ordered all new stainless parts.
When I took apart the factory setup, I carefully laid aside the shims so I could reinstall them in their original orientation. Unfortunately, they wouldn’t all fit, so I took the new ones and roughly centered the trailing arm until I could get the car aligned.
Now, bolt the halfshaft to the hub. Since I had a pair of Dragvette halfshaft loops on the car, I slipped those over the halfshafts before bolting them up. Be sure to keep the included French locks in place while installing the bolts. My assembly manual shows a range of 60-90 lb-ft for them; given their function, I went with 90.
The new setup should be pretty tight, so be aware it may take some wrestling to get the bolt holes lined up. You may find it helps to put the car in Neutral so you can rotate the halfshafts to align everything. Keep in mind that you’ll need to put it back in Park to torque down the bolts, so expect to spend a lot of time getting out from under the car, changing the gear, sliding back underneath, and so on.